1. Field of the Invention
This invention relates to the field of assaying platelet factor 4 superfamily members (hereafter "PF4A") and the preparation of agonists and antagonists to the members of this family, in particular, antibodies to these receptors.
2. Description of Background and Related Art
While interleukin-8 was initially identified as a chemoattractant for neutrophils, and was known to bind a receptor on neutrophils (Samanta et al., J. Exp. Med., 169: 1185-1189 [1989]; Besemer et al., J. Biol. Chem., 264: 17409-17415 [1989]; Grob et al. J. Biol. Chem., 265: 8311-8316 [1990]), it has in addition a wide range of pro-inflammatory activities including the stimulation of degranulation and the upregulation of the cell adhesion molecule MAC-1 and of the complement receptor CR1. Oppenheim et al., Annu. Rev. Immunol., 9: 617-648 (1991).
IL-8 is secreted by many cell types in response to pro-inflammatory stimuli such as IL-1.beta., TNF, and endotoxin and is a member of a family of ten or more pro-inflammatory cytokines with an M.sub.r .about.10,000. Oppenheim et al., supra. This larger family of proteins is called the platelet factor 4 superfamily. Wolpe et al., FASEB J., 3: 2565-73 (1989). Some members of the platelet factor 4 superfamily, in general the subset referred to as C--X--C peptides (including IL-8), possess neutrophil agonist activity, e.g. neutrophil activating protein-2 (NAP-2), platelet factor 4 and NAP-3 (melanoma growth-stimulating activity [MGSA]/gro), all of which are encoded by genes on human chromosome 4. Other members of this family, the C--C peptides, encoded by genes on human chromosome 17, are not neutrophil agonists, and include RANTES, macrophage chemotactic and activating factor (MCAF). Hereafter "PF4A" means the PF4 superfamily. Oppenheim et al., supra.
The IL-8 receptors are members of the superfamily of seven transmembrane, G-protein linked receptors. Taylor, Biochem. J., 272: 1 (1990). This family of receptors includes several hundred different receptors among which the .beta.-adrenergic receptor (Strader et al., FASEB, 3: 1825 [1989]; Dixon et al., EMBO J., 6: 3269 [1987]), the muscarinic and cholinergic receptors (Kubo et al., Nature, 323: 411 [1986]; Peralta et al., EMBO J., 6: 3923 [1987]), the c5a and fMet-Leu-Phe receptors. Two types of IL-8 receptors have been described: type A (IL8R-A) (Holmes et al., Science, 253: 1278 [1991]) and type B (IL8R-B) (Murphy and Tiffany, Science, 253: 1280 [1991]) receptors. These two receptors share 77% amino acid identity and have 29-34% sequence homology to C5a and fMet-Leu-Phe. Holmes et al., supra. IL8R-A has a high affinity (2 nM) for IL-8 only, while IL8R-B has a high affinity (2 nM) for both IL-8 and MGSA. The function and expression level of each receptor on these cells have yet to be determined.
It is an object of this invention to identify receptors for the PF4A superfamily (hereinafter "PF4AR").
It is another object of this invention to obtain DNA encoding or hybridizing to these receptors, and to express the receptors in host cells.
It is an additional object of this invention to provide isolates of PF4AR for diagnostic and therapeutic purposes.
A still further object is to obtain DNA encoding variants of such receptors and to prepare such variants in recombinant cell culture.
A yet further object is to identify and prepare antibodies to receptors for the PF4A superfamily (hereinafter "PF4AR").
It is still another object to provide a method for treating or preventing an inflammatory response in a mammal using an antibody to such receptors.
These and other objects of this invention will be apparent from the specification as a whole.